Table 1: IAQ objectives for offices & public places

Parameter

Unit

8-hour average a

Excellent Class

Good Class

Room Temperature

°C

20 to <25.5 b

< 25.5 b

Relative Humidity

%

40 to <70 c

< 70

Air movement

m/s

< 0.2

< 0.3

Carbon Dioxide (CO2)

ppmv

< 800 d

< 1,000 e

Carbon Monoxide (CO)

μg/m3

< 2,000 f

< 10,000 g

ppmv

< 1.7

< 8.7

Respirable Suspended Particulates (PM10)

μg/m3

< 20 f

< 180 h

Nitrogen Dioxide (NO2)

μg/m3

< 40 g

< 150 h

ppbv

< 21

< 80

Ozone (O3)

μg/m3

< 50 f

< 120 g

ppbv

< 25

< 61

Formaldehyde (HCHO)

μg/m3

< 30 f

< 100 f, g

ppbv

< 24

< 81

Total Volatile Organic Compounds (TVOC)

μg/m3

< 200 f

< 600 f

ppbv

< 87

< 261

Radon (Rn)

Bq/m3

< 150 i

< 200 f

Airborne Bacteria

cfu/m3

< 500 j, k

< 1,000 j, k

 

Legends:

  1. In some cases, it may not be practicable to take 8-hour continuous measurement. In these circumstances, surrogate measurement (i.e. an intermittent measurement strategy based on the average of half-an-hour measurements conducted at four time-slots) is also accepted.
  2. EMSD (1998), Guidelines on Energy Efficiency of Air Conditioning Installations
  3. Indoor Air Quality guideline value for Japan (Law of Maintenance of Sanitation in Building) and South Korea (Public Sanitary Law).
  4. US EPA (1996), Facilities Manual: Architecture, Engineering, and Planning Guidelines. Maximum Indoor Air Concentration Standards.
  5. Indoor Air Quality guideline value for Australia (Interim National Indoor Air Quality Goals), Canada (Indoor Air Quality in Buildings: A Technical Guide), Japan (Law of Maintenance of Sanitation in Building), South Korea (Public Sanitary Law), Singapore (Guidelines for Good Indoor Air Quality in Office Premises/building), Sweden (Ventilation Code of Practice) and Norway (Recommended Guidelines for Indoor Air Quality).
  6. Finnish Society of Indoor Air Quality and Climate (2001), Classification of Indoor Climate 2000: Target Values, Design Guidance and Product Requirements.
  7. WHO (2000), Guidelines for Air Quality
  8. EPD (1987), Hong Kong Air Quality Objectives under the Air Pollution Control Ordinance (Cap. 311)
  9. US EPA(1987): US EPA Guideline for Radon in Homes due to Natural Radiation Sources (Note: 4 pCi/L or 150 Bq/m3 is EPA Action Level)
  10. ACGIH (1986), ACGIH committee activities and reports “Bioaerosols: Airborne viable microorganisms in office environments: sampling protocol and analytical procedures”, Applied Industrial Hygiene.
  11. The exceedance of bacterial count does not necessarily imply health risk but serve as an indicator for further investigation.
  12.  

Table 2: IAQ objectives for individual VOCs (for good class TVOC objective only)

Compound

Good Class

Benzene

5 ppbv a
(16.1 μg/m3)

Carbon tetrachloride

16 ppbv b
(103 μg/m3)

Chloroform

33 ppbv b
(163 μg/m3)

1,2-Dichlorobenzene

83 ppbv c
(500 μg/m3)

1,4-Dichlorobenzene

33 ppbv c
(200 μg/m3)

Ethylbenzene

333 ppbv c
(1,447 μg/m3)

Tetrachloroethylene

37 ppbv a,c
(250 μg/m3)

Toluene

290 ppbv a
(1,092 μg/m3)

Trichloroethylene

143 ppbv a,d
(770 μg/m3)

Xylene (o-, m-, p-isomers)

333 ppbv e
(1,447 μg/m3)

 

Legends:

  1. WHO (1995), Updating & Revision of the Indoor Air Quality Guidelines for Europe
  2. 1/300 of ACGIH TLV-TWA, ACGIH (1996), ACGIH Threshold Limit Values for Chemical Substances in the Work Environment.
  3. A continuous exposure guideline value as recommended by WHO
  4. The Royal Society, London (1983) “Risk level where very few would consider action necessary, unless clear causal risk with consumer products”
  5. Labour Department (2002), Code of Practice on Control of Air Impurities (Chemical Substances) in the Workplace
  6. Note: All conversion calculations are based on data from NIST Standard Reference Database 69 - March 2003 Release: NIST Chemistry Webbook.